NOTES
960
15.85 g. (41%) of 1-methylcyclohexene, b.p. 109-109.5", nZ6D Extraction of the olefin was 1.4509 (lit.az 109.5", 7 ~ 2 01.4505). ~ not quantitative as shown in a blank experiment; authentic 1-methylcyclohexene (Aldrich, distilled), subjected t o the same isolation procedure, was recovered in 707, yield. Reduction of 2a-Bromocholestanone .-To a 100-ml. threenecked flask containing a magnetic stirrer and attached through a condenser to a gas buret were added 13 ml. (0.4 mole) of hydrazine hydrate, 2 g. (20 mmoles) of potassium acetate, and 10 ml. of cyclohexene. The flask was heated until the cyclohexene boiled, and a solution of 2.004 g . (4.3 mmoles) of 2abromocholestanone in 30 ml. of cyclohexene was added dropwise over 10 min. while maintaining stirring and boiling. Heating was continued for 30 min. The light yellow mixture was cooled, extracted with ether-water, dried, evaporated, dissolved in hexane, and percolated through a column of acid-washed alumina (Merck). Evaporation of the filtrate yielded 995 mg. (64y0) of 2-cholestene, m.p. 72-74', [:ID $64". Recrystallization from ether-ethanol (2: 1) gave white needles of 2-cholestene in 95Y0 yield, m.p. 73-75', [a10+65". Poorer results were obtained if the reagents were all mixed before heating. Thus a mixture of 2.009 g. of 2a-bromocholestanone, 13 ml. of hydrazine hydrate, 2 g. of potassium acetate, and 13 i d . of cyclohexene heated to reflux yielded a darker reaction mixture and only 269 mg. (19%) of 2-cholestene, m.p. 72-74'. 2~,3p-Dibromocholestane.-Toa solution of 109 mg. (0.29 mmole) of 2-cholestene, m.p. 73-75', in 2 ml. of ether was added dropwise a solution of bromine in acetic acid until a slight excess of bromine was present. Evaporation of solvent and crystallization of the residue from ether-ethanol gave 76 mg. (49%) of white plates of 2u,3p-dibromocholestane, m.p. 123-124', lit.28 m . p . 125". Hydrogenation of 2-Cho1estene.-Microhydrogenation of 40.6 mg. (0.11 mmole) of 2-cholestene, m.p. 72-74', in acetic acid using 10% palladium on carbon as catalyst, led to the slow (ca. 6 hr.) uptake of 1.00 equivalent of hydrogen. Work-up of the solution gave a light yellow residue which was dissolved in hexane and percolated through a short alumina column. Evaporation of the filtrate yielded 34 mg. (8574) of crude cholestane, m.p. 75-80", The melting point was raised to 79-80", lit.28 m.p. 80", by crystallization from ether-ethanol.
VOL. 29
and subsequent disproportionation of the ether to give I and 1,3,5-~ycloheptatriene(II).*,3 We have observed a direct oxidation of I1 by selenium dioxide in buffered aqueous dioxane to give I in about 25% yield. This reaction, though not high in yield, affords a simple one-step preparation of I from commercially available starting materials. The reaction can readily be adapted to large scale, and the inorganic product, selenium, can be recovered and reoxidized to selenium dioxide if desirable.6 Experimental Preparation of Tropane.-To a solution of potassium dihydrogenphosphate (13.5 g., 0.1 mole) in water (33 ml.) was added 1,4-dioxane (330 mi.), 1,3,5-cycloheptatriene (43.0 g., 0.46 mole, Shell Chemical Corp., contained 6% toluene), and selenium dioxide (53.0 g., 0.48 mole, Matheson, Coleman and Bell). The mixture was warmed on the steam bath (90") for 15 hr., allowed to cool to room temperature, and then filtered. The filtrate was poured into water (750 ml.) and extracted three times with 250ml. portions of methylene chloride. The organic extract was washed with 10% sodium bicarbonate, dried over anhydrous magnesium sulfate, filtered, and concentrated in uacuo to a dark brown liquid. Distillation of this liquid gave 12.8 g. ( 2 5 % ) of pale yellow tropone, b.p. 91-92' a t 4 mm., nZaD1.6152. The infrared spectrum of this material ww identical with that reported by Doering.6
Acknowledgment.-The author wishes to thank Shell Chemical Corporation for its generous supply of 1,3,5cycloheptatriene. (6) N. R a b j o n , "Organic Reactions." CON. Val. V. R. Adams, E d . , J o h n Wiley a n d Sons, New York, N. Y . , 1949, p. 345.
The Reaction of Chlorocarbene with Styrene (32) G . Egloff, "Physical Constants of Hydrocarbons," Val. 2. Reinhold Publishing Corp., New York, N . Y., 1940, p. 326.
Tropone.
Selenium Dioxide Oxidation of 1,3,5-Cycloheptatriene
WENDELLL. DILLING
Edgar C . Britton Research Laboratory, The Dou, Chemical Company, Midland, Michigan Received August 99, 1963
PHILLIP RADLICK
A number of carbenes or "carbene-like" species have been added to styrene to give substituted phenylcycloDepartment of Chemistry, University of California, Riverside, propanes. Closs and co-workers2 have generated California chlorocarbene from methylene chloride and methyl- or n-butyllithium and added it to various olefins to give Received Sovember 7 , 1963 substituted chlorocyclopropanes. The work which is now reported was undertaken to study the addition of There are several methods known for the preparation chlorocarbene to styrene. of tropone (2,4,6-cycloheptatrien-l-one, I) . l P 5 They When ethereal n-butyllithium, prepared from n-butyl range in scope from the degradation of tropinone4 to produce I, to the formation of bis-2,4,6-cycloheptatrien- bromide and lithium, was allowed to react' with methylene chloride in the presence of excess styrene, two stereoI-yl ether (111) from the hydrolysis of tropilium salts isomeric 1-chloro-2-phenylcyclopropaneswere isolated in low yields in addition to several gaseous products. The yields of 1 (4.1%) and 2 (4.9%) are based on distilled material, assuming equal thermal conductivities on gas chromatographic (g.c.) analysis. The structural
R
0 I
0 II
(1) J. Birch. M . Graves, a n d F. Stansfield, P r o c . Chem. Soc., 282 (1962). ( 2 ) T . Sozoe. T. Ikemi, a n d H. Sugiyama. Chem. I n d . (London), 932 (1960).
(3) h. P. ter Bora, Hela. Chim. Acta, 43, 457 (1960). (4) .J. b I e i n a a l d . S. Emernian, N. Yang, a n d G. Biichii, J . A m . Chem. Soc.. 7 7 , 4801 (1955). ( 5 ) M von E . Doering a n d F. Detert. ibid., 73, 877 (1951).
(1) ( a ) P. S.Skell and A. Y. Garner, J . A m . Chem. Soc., 7 8 , 5430 (1956): (b) W. J. Dale a n d P. E. Swartzentruber. J . Org. Chem.. 24, 955 (1959): (c) A. Nagasaka a n d R . Oda, Kogyo Kagaku Zasshi, 69, 1024 (1956): (d) H. D . Hartzler, J . Am. Chem. Soc.. 83, 4990 (1961); (e) A . Burger and W. L. Yost, ibid., TO, 2198 (1948); (f) R . J. Mohrbacher and N . H . Cromwell, ibid., 79, 401 (1957); (9) H. E. Simmons and R . D. S m i t h , ibid.. 81, 4256 (1959); (h) G . Wittig a n d K. Schwaraenbach, Ann., 660, 1 (1961). (2) G . L. Closs and L. E. Closs, J . A m . Chem. Soc.. 82, 5723 (1960), and subsequent papers.
APRIL, 1964
CGHS-CH=CH2
cv +
96 1
NOTES
+
bci+
C6H5 CH&12
-k
n-C4H,Li
+
1 n-C4Hlo
f
butene18
4- pentene/s
n
L
assignments are based primarily on the nuclear magnetic resonance (n.m.r.) spectra and to a lesser extent on their physical properties. The n.m.r. spectrum (CCI,) - pp - 3 . 4 PP of 1 showed a broad multiplet centered at 6 -7.073 Fig. 1.-Partial n.m.r. spectrum of trans-1-chloro-2-phenyl(;i.00)4 for the aromatic protons, an octet a t -3.07 cyclopropane (1). (1.00) for the proton on the chlorine-bearing carbon, an octet at -2.28 (1.00) for the benzylic proton, and a t least eight peaks at - 1.35 (2.50) for the two remaining cyclopropyl protons. Isomer 2 also showed four sets of peaksat 6 -7.20 (5.00, singlet), -3.28 (1.00), -2.27 (1.08), and -1.28 (2.10), respectively. The high resolution n.m.r. spectra of the proton, H A , on the chlorinebearing carbon and the benzylic proton, HG, for the two isomers are shown in Fig. 1 and 2. Analysis of these spectra show the coupling constants between HA and HB to be 3.3 c.p.s. for the isomer assigned the trans structure and 7.7 C.P.S. for the other isomer. It has - PP. - 3.28 PW been fairly well-established that cis protons on a cycloFig. 2.-Partial n.m.r. spectrum of cis-1-chloro-2-phenylcyclopropane ring have a larger coupling constant than do propane (2). trans proton^.^ The relative chemical shifts for HA of the two isomers also are consistent with the assigned The identity of the cyclopropanes was based on elestructures, since the proton on the chlorine-bearing mental analyses, spectral data, and comparison of the carbon of the cis isomer is usually found a t a lower physical properties with the literature values. fieid.5h8c,6 The relative boiling points and refractive indices of 1 and 2 are also in agreement with the asC6H6-CH=CHz f CH2Cl, CH3Li C,H,U signed structures. -4number of cases have been re3 ported in which the cis cyclopropyl compounds had the higher values for both of these physical proper tie^.^^^^^^^^^' + C 6 H 5 7 CH3 CH4 CHICHI CHt=CHz + The slight predominance of the cis isomer isolated is in accord with the findirgs of Clcss and c o - ~ v o r k e r s ~ , ~ ~ 4 who also found a preference for the cis isomers. HowC3H4 C H ~ C H Z C H+~ CHXH=CH, + butene/s + ever, this result may be fortuitous, since the yields are pentene/s + CHaCl quite low and may only reflect the product distribution The mechanism of the latter reaction has not been after a portion of the primary product has reacted determined, but several possible reaction paths could further. An indication that the latter may have ocbe visualized. Initial formation of a complexed carcurred was found in the isolation of a high-boiling liquid bene (:CH2)9 could give use to 3. The presence of which contained cyclopropyl protons as shown by n.m.r. lithium iodide could account for the formation of this spectroscopy. The origins of the n-butane, butene/s, complexed carbene in a manner analogous as that deand pentene/s in this type of reaction have been disscribed by Schollkopf and Paust'O for the formation of cussed elsewhere. 2.8 alkoxy carbenes. Formation of methylcarbelie' could In contrast to the above results utilizing n-butyllead to 4. Alternatively, various combinations of lithium, the reaction of methyllithium, prepared from halogen-metal exchange, alkylation, and hydrolysis of methyl iodide and lithium, with methylene chloride and 1 or 2 could give 3 and 4.12 The gaseous products styrene in ether a t either 3-10' or -70' led to the probably arose from interaction of methyllithium, formatiori of phenylcyclopropane (3, 10%) and 1methylene chloride, and chlorocarbene. Reactions methyl-2-phenylcyclopropane (4, 20%) in addition to a between methylene halides and organometallic comcomplex mixture of gases. S o 1 or 2 could be detected. pounds to give products analogous to some of those re(3) 6 in p.p.111.from tetraniethylsilane used a s an internal reference. ported here have been described.13 2.28
2.27
+
+
+
+
+
+
(4)
Integrated area.
(5) (a) J. I). Graham a n d M. T. Rogers A m . Chem. Soe., 84, 2249 (1962); ( b ) G . L. Closs. R. A . Moss, a n d J. J. Coyle, ibid., 84, 4985 (1962); ( c ) 1 ) . Sesferth. H.Yaniazaki, and D. L.Alleston, J . O r g . Chem., 28, 703 I1963). (6) I ) . E. Applequist and .A. H. Peterson, J . A m . Chem. Soc.. 8 2 , 2372 ( 1960).
(7) R . G. Kelao, K . W , Greenlee, J . M . Derfer, and C. E . Boord, ibid., 77, 1751 (1955). (8) (a) J. F. Eastham a n d G. W. Gibson, J . Org. Chem., 28, 280 (1963); ( h ) G . 1,. Closs a n d L. E. Closs, J . A m . Chem. Soc., 81, 4996 (1959); (c) C. I.. Closs. ibnd., 84, 809 (1962).
(9) For possible related reactions, see (a) R . T. Miller, J r . a n d C. S . Y. Kim, ibid., 81, 5008 (1959); (h) L. Friedman a n d J. G. Berger, % b i d . . 82, 5758 (1960); (c) J. Hine, "Physical Organic Chemistry." 2nd E d . , McGrawHill Book Co., New York, N . Y.. 1962, p . 500. (10) U. Schollkopf and J. P a u s t , Angeu. Chem., 75, 670 (1963). (11) G . L. Closs and L. E. Closs, Tetrahedron Letters, No. 10, 38 (1960). ( 1 2 ) For pertinent references, see (a) H. M . Walhorsky. Record Chem. Proer. (Kresge-Hooker Sci. Lib.). 23, 75 (1962); (h) H . M . M-alborsky and F. J. Inipastato, J . A m . Chem. S o c . , 81, 5835 (1959), ref. 6. (13) (a) A . A . Morton and F. Fallwell, .Jr., ibid., 60, 1429 (1938); (h) G . W i t t i g a n d H . Witt, Chem. B e r . , 74B,1474 (1941).
XOTES
962
Reaction of methylene bromide with methyllithium and styrene gave 3 as the only identifiable cyclopropyl derivative (1.3%). The formation of 3 is analogous to the results obtained by Miller and Kim with cyclohexene. 9a.14 C&,-CH=CH2
+ CH2Br + CH3Li C&&--
